Throttle control mechanism for an engine

ABSTRACT

The throttle of an engine is controlled to maintain its speed substantially constant in spite of variations of load upon it. The illustrated load comprises hydraulically operated equipment in a hydraulic system powered by a pump driven by the engine. Throttle control mechanism comprises a pair of cylinders supplied from fluid pressure in the hydraulic system. Pistons in the respective cylinders are connected by pivots with a control arm linked to the throttle control. When equipment is hydraulically operated from the hydraulic system, the fluid back pressure against the pump increases, this back pressure being greater the greater the hydraulic load. The increased load on the engine from the pump would slow the engine down if its throttle opening were to remain at its original setting. The function of the throttle control mechanism operated from the hydraulic pressure from the pump, is to move the control arm by a proper amount to open the throttle a sufficient amount to keep the engine speed up to its normal value regardless of changes of load. Compression springs adjustable from adjustable bushings at the cylinders provide a counter-pressure opposing the pressure from the fluid in the cylinders and by suitable adjustment of these bushings the throttle can be made to open or close further in accordance with changes of load to maintain substantially constant engine speed which will maintain uniform flow of fluid through the hydraulic system regardless of load thereon.

This is a division of application Ser. No. 540,396, filed Jan. 13, 1975now U.S. Pat. No. 3,973,472 granted Aug. 10, 1976.

This invention relates to a mechanism and system for controlling anengine throttle to maintain the engine speed substantially constant inspite of changes of load on the engine.

It is well known that the speed of an internal combustion engine such ascarburetor-operated engine of which the common gasolene engine istypical, or an injector type engine generally known as a diesel engine,decreases with increase of load on the engine unless the throttlecontrolling the carburetor or injector is correspondingly openedfurther. There are many instances where the load on the enginefrequently changes and it is disadvantageous to have to tend thethrottle to adjust it manually to compensate for these changes.

A typical instance is the driving of a hydraulic ram or the like by apump in a hydraulic system in which the pump is driven by the engine.Another instance is in the operation of a Kelly drive for an earth augerwhich involves the extension and retraction of a shaft carrying theauger and may also involve the operation of a motor for rotating theauger shaft. These are only some of the many situations in which theloading of an engine tends to slow it down. In the operation of suchsystems the slowing down of the engine is undesirable, and can beavoided to a great extent by adjustment of the engine throttle.

An object of the present invention is to provide a mechanism and systemfor making such throttle adjustments automatically.

A related object is to provide a hydraulic pumping system containing thethrottle control mechanism.

A further related object is to provide such a hydraulic system adaptedto drive equipment.

The invention is carried out by provision of a throttle controlmechanism operable from a hydraulic circuit and provided with linkagemeans for controlling the throttle in accordance with pressure in thehydraulic system so that when the hydraulic pressure rises the throttleopens further and when the pressure falls the throttle moves to a moreclosed position. The throttle control mechanism comprises a pair ofhydraulic cylinders each containing a piston connected at spacedpositions on a control member or arm which may be termed a hydraulicfulcrum linked to the throttle of the engine. There is a hydraulic fluidinlet to the cylinders so that changes of fluid pressure move bothpistons and also the floating fulcrum member.

A feature of the invention resides in the making of one of the cylindersand pistons of greater diameter than the other.

A further feature resides in the use of means applying pressure to thepistons in opposition to the fluid pressure from the pump.

A further feature resides in the provision of means for adjusting thesaid opposing pressures.

Another feature resides in relating the position where the linkage isattached to the control arm relative to the positions where the pistonsare connected to the control arm so that movements of the pistonsproduce desired movements of the throttle under different conditions ofhydraulic pressures at the pump.

By reason of the arrangement of this invention it is possible tomaintain the pump speed and hydraulic fluid flow in the hydraulic systemsubstantially constant over a wide range of fluid pressures resultingfrom varying hydraulic loads on the pump.

The foregoing and other features of the invention will be betterunderstood from the following detailed description and the accompanyingdrawing of which:

FIG. 1 shows a system containing a throttle control mechanism accordingto this invention;

FIG. 2 is a longitudinal cross-section view of the throttle controldevice included in the system of FIG. 1, the cross-section being takenat line 2--2 of FIG. 3;

FIG. 3 is a cross-section view taken at line 3--3 of FIG. 2; and

FIG. 4 is an end view looking from line 4--4 of FIG. 2.

In FIG. 1 there is shown a hydraulic system controlling the throttle ofan engine which may for example be an internal combustion engine havinga carburetor or a diesel engine having an injector. No part of theengine is shown in FIG. 1 except for its representation by a rectangle23 and a support member 10 indicated as being mounted on a base 10a, towhich there is attached a throttle arm 11 pivoted to support 10 at apivot 12. Assuming that the engine is on a vehicle to be driven by theengine there will be a lever 13 from a foot pedal (not shown), attachedto the throttle arm at some distance from its pivot. A compressionspring 14 compressed between the lever arm 11 and a member 15 which isfixed relative to support 10 urges the lever arm to rotate in thecounter-clockwise direction as shown in FIG. 1, which will applypressure to the foot pedal arm in the direction shown by arrow 16.

There is associated with the engine a hydraulic system 17 having areservoir 18 containing hydraulic fluid 19. The reservoir is enclosedexcept for an outlet conduit 20 and a return conduit 21. The outletconduit 20 connects with a pump 22 driven by the engine, represented byrectangle 23, as indicated by the dotted line 24. The high pressure sideof the pump supplies a conduit section 20a leading to a relief valve 24of a well known type which operates in a well known manner to bleed offfluid received from conduit section 20a, at the outlet from the pump, ifthe pressure at the relief valve exceeds a predetermined set value, inwhich event the fluid thus bled off is sent through a by-pass conduit 26to the return conduit 21 to the reservoir, thus keeping the pressurefrom the pump at or below the set pressure limit. Down stream from therelief valve 25 there is shown a number of devices operable from thepressurized hydraulic fluid. Thus a conduit section 20b carries thepressurized fluid to valves 27, 28 and 29 arranged in tandem along theconduit sections 20 b, 20c and 20d, respectively, the last valveconnecting with the return conduit 21.

Valve 27 has connected to it two conduits 30 and 31 which communicatewith respective ports 32 and 33 at opposite ends of a hydraulic cylinder34 which is of a well-known type having a rod or a member 35 protrudingfrom it and connected with a piston (not shown) within the cylinderbetween the ports 32 and 33. The valve 27 is of a well-known typeoperable manually or by remote control to any of three positions. In afirst position it puts the pressurized fluid from conduit 20b intoconduit 30, but not into conduit 31, to move member 35 downward, andalso receives and transmits to conduit section 20c, fluid forced out ofthe cylinder through conduit 31. In a second position it putspressurized fluid from conduit 20b into conduit 31, but not into conduit30, to move the member 35 upward, and at the same time receives andtransfers fluid force out through port 32 through conduit 30, intoconduit section 20c. In the third position it puts pressurized fluidfrom conduit 20b into communication with conduit 20c, while blockingcommunication of both conduits 30 and 31 to either of conduits 20b and20c.

The other valves 28 and 29 are similar to valve 27 and are connectedwith hydraulic conduits in the same manner as in the case of valve 27.Thus, valve 28 connects with respective conduits 36 and 37 leading to afluid motor 38 so that the motor may be turned in either direction ornot at all, depending on which one of the three positions of valve 28 isselected. Similarly, valve 29 has connected to it conduits 39 and 40which lead to ports at opposite ends of a cylinder 41 containing apiston actuated member 42, in a manner similar to the hydraulicarrangement associated with cylinder 34. Similarly, the member 42 ofcylinder 41 may be operated in either direction, or not at all,depending upon the particular one of the three positions of valve 29which is selected. Regardless of which positions the valves 27, 28 and29 are put into there will always be hydraulic fluid circulating in thedirection of arrows 9 through conduit 20 and through all of these valvesto conduit 21 and back to the reservoir.

In the arrangement shown in FIG. 1 it is assumed, as an example, thatthe cylinders 34 and 41 and the motor 38, the reservoir 18 and the pump22 are mounted with the engine 23 as equipment on a portableearth-drilling rig. Thus the cylinder 34 and its ram 35 may be used in awell-known manner for leveling the rig; the shaft 42 of cylinder 41 maybe provided with an earth-drilling auger in a well-known manner; and themotor 38 may be coupled with the shaft 42 to rotate the shaft relativeto its cylinder for drilling purposes. Such equipment is well known inthe drilling art. It should be understood that the cylinders and themotor illustrated are shown simply as examples of typical equipment, andthat more or less of such equipment, or different equipment, operatedhydraulically may be utilized in such a system.

It is seen that when the valves 27, 28 and 29 are all turned to the sameposition in which the hydraulic fluid flows directly from conduits 20a,20b, 20c and 20d to return conduit 21 the engine 23 need do onlysufficient work on pump 22 to move the fluid in this path of travel,which will be opposed only by friction in the conduits and valves. Butwhen any one or more of the valves 27, 28 and 29 is moved to a positionin which work is being done at one or more of cylinders 34 and 41 andmotor 38, the engine must work harder in order to do this work. Assumingthe engine throttle to be set at some particular position, the effect ofthe increased load at any one or more of components 34, 41 and 38 willslow down the engine, which will result in a corresponding decrease ofrate of flow through pump 22 and a corresponding slowing of movement ofcylinder members 35 and 42 and of motor 38.

In accordance with the present invention provision is made forautomatically controlling the throttle so that the engine will maintainits speed regardless of the load on it. This is done by use of athrottle control mechanism 43 hydraulically connected to conduit 20a bymeans of a fluid conduit 44.

The throttle control mechanism 43 is shown in detail in FIGS. 2, 3 and4. It comprises a housing or block 45 of generally rectangularcross-section within which there are formed two cylinders 46 and 47,cylinder 46 being of substantially greater diameter than cylinder 47.Cylinder 46 contains a piston 48 reciprocatable longitudinally throughthe cylinder and sealed to the inner cylinder wall by an O-ring 49.Cylinder 46 is opened to the exterior at one end 50 of the block but isclosed from the exterior at the other end 51 of the block except for aninlet opening or port 52 which provides communication from the exteriorof the block to region 53 within the cylinder 46 between the piston andthe end 51. A piston rod 54 is attached to the side of piston 48opposite the region 53 and extends along the longitudinal axis of thecylinder to the exterior of the block, through a plug bushing 55provided with a central axial opening 56 for the purpose. There isenough clearance between piston rod 54 and the opening 56 to vent thespace within the cylinder 46 back of the piston for passage of air whenthe piston moves. Plug bushing 55 is provided with threads 57 forengaging corresponding threads on the interior wall of a cylinder sothat the bushing may be moved longitudinally through the cylinder withinlimits determined by the extent of the cylinder threads. A helicalcompression spring 58 is placed around the piston rod 54 with itsrespective ends adapted to engage the bushing and the piston.

The second cylinder 47 is positioned in the block with its longitudinalaxis parallel to that of the first cylinder 46. Cylinder 47 contains apiston 59 reciprocatable longitudinally within this cylinder andprovided with an O-ring seal 60 to provide fluid sealing between thepiston and the inner wall of the cylinder. A piston rod 61 is attachedto the piston so that it extends longitudinally outward through anopening 62 through end 50 of the block in a direction parallel to thepiston rod 54. An O-ring seal 63 at opening 62 provides for fluidsealing between the piston rod 61 and the wall of opening 62. The end ofcylinder 47 opposite the opening 62 opens to the exterior of the blockat the end 51 of the block. The end of the cylinder at this opening isprovided with threads 64 which are engaged by corresponding threads of ascrew plug 65 provided with a slot 66 at its outer end for turning by ascrew driver. The inner end of screw plug 65 is provided with anunthreaded shank portion 67 adapted to engage the end of a helicalcompression spring 68, the other end of which is adapted to engage theside of piston 59 opposite its piston rod. A longitudinal ventpassageway 76 is provided through screw 65 for passage of air whenpiston 59 moves. Tapped holes 77 and 78 are for set screws to bind therespective plugs 55 and 65 after they are adjusted.

A passageway 69 is formed through the block so that one of its endscommunicates with the region 53 within cylinder 46 and the other endcommunicates with a region 70 of cylinder 47 between the piston and theopening 62 through the block.

An arm 71 outside the block is attached to piston rod 61 by a pivot pin72 and also attached to piston rod 54 by a pivot pin 73. A chain 74,shown in FIG. 1, is attached to the arm 71 at a position 75 at theopposite side of pivot 73 from pivot 72. The distance along the armbetween pivot 73 and position 75 is preferably greater than the distancebetween pivots 72 and 73 and may conveniently be made about twice thedistance between the two pivot pins. The other end of chain 74 isattached to the throttle arm 11 so that when the position 75 of arm 71moves to the right as seen in FIG. 1 the chain 74 can pull on thethrottle arm 11 to pivot it in the clockwise direction, that is, thesame direction that pushing the foot pedal 13 and lever to the rightwill do. When the position 75 moves to the left the pressure fromcompression spring 14 then pivots the throttle arm 11 correspondingly inthe counter-clockwise direction, assuming there is no pressure on thefoot pedal. To permit adjustment of the position of attachment of thechain 74 to arm 71 this end of the chain may be provided with a hook orthe like, and at position 75 of the arm there may be a hole orequivalent to which the hook can be engaged. Furthermore a number ofelements 75a, 75b . . . 75n may be provided along the arm so that thehook can be attached to any one of them. Selection of the position ofattachment of the chain to the arm controls the effects on the throttle,of increments of movement of the two pistons.

The operation of the system is as follows: Assume that the pump 22 isset into operation by the engine while all of valves 27, 28 and 29 arepositioned to send the fluid directly from the pump through conduits20a, 20b, 20c, 20d and 21 back to the reservoir. The engine then will bedelivering relatively little horsepower as there will be little backpressure against the pump. But if any of the components 34, 38 and 41 isset into operation by appropriate turning of any of the valves 27, 28 or29 the back pressure against the pump will increase and the pump willexert a greater load on the engine which would slow the engine down ifthe throttle control mechanism were not in operation. If an additionalone or ones of the components 34, 38 and 41 be turned on, the enginewould correspondingly slow down still further, in the absence of thethrottle control. It is ordinarily desired that a normal fluid flowshall take place in the hydraulic circuit of each of components 34, 38and 41 regardless of how many of them are turned on at the same time.The throttle control mechanism 43 is capable of maintaining the enginespeed substantially constant throughout such changes of load on theengine and therefore of maintaining the same pumping rate from the pump.

At all times while the pump is being driven by the engine, fluid iscirculating through the hydraulic circuit from the reservoir through thepump and conduits 20a, 20b, 20c, 20d and 21 to the reservoir; and alsoconduit 44, chamber 53, conduit 69 and chamber 70 are filled with thefluid. Whatever pressure exists at the outlet of the pump is applied atregion 53 tending to urge piston 48 to move toward the plug bushing 55.Since this pressure is also conveyed to region 70 of cylinder 47 thefluid pressure will tend to move piston 59 toward screw plug 65. Thecompression springs 58 and 68 tend to oppose such movements of thepistons. The fluid pressure at inlet port 52 will vary with variationsof fluid back pressure at the pump, and the pistons 48 and 59 will cometo positions in the respective cylinders in which the counter pressuresof the respective compression springs 58 and 68 are in balance with thefluid pressures. Since the block 45 of throttle control 43 is fixedrelative to the support 10 for the throttle arm 11 the arm 71 willassume different positions and attitudes relative to the throttle arm11, depending upon the fluid pressure at conduit 20a.

Considering the piston rod 54, whenever the fluid pressure at chamber 53tends to rise, this piston rod tends to move to the right, withreference to FIG. 1, thereby tending to open the throttle further.Considering the piston rod 61, whenever the fluid pressure at chamber 70tends to rise this piston rod tends to move to the left with referenceto FIG. 1 thereby also tending to open the throttle further. Since thearea of piston 48 is much greater than that of piston 59, the conditionof a relatively low pressure will move piston 48 while imparting littleor no motion to piston 61. But when the fluid pressure increases, thepiston 48 moves closer to the bushing plug 55, and when it hascompressed the spring 58 as far as the spring can be compressed, thepiston 54 can have no further movement even though the fluid pressurerises further. At these relatively high fluid pressures, the pressureagainst the smaller piston 59 becomes sufficient to move the piston 59toward the screw plug 65 to impart movement to the piston rod 61, andwhen the fluid pressure continues to increase further, the piston 59will continue to move further toward screw plug 65 while compressingspring 68 even up to the highest pressures developed in the system.

It is noted that a given increment of movement, for example onemillimeter, of piston rod 61 has a greater effect on movement ofposition 75 on arm 71 than does the same increment of movement of pistonrod 54, for the reason that pivot point 73 lies between pivot point 72and position 75, and the distance between pivot 73 and position 75 isgreater than the distance between pivots 72 and 73.

When the pump is disconnected from the engine and there is no load onthe engine the throttle will ordinarily be adjusted for a proper idlingspeed. Assuming that the engine is in a vehicle, the engine may bespeeded up from its idling speed by depressing the foot pedal and thevehicle may be driven by the engine on a roadway in a well-known manner,without any effect from the throttle control unit 43. When the vehiclehas been thus moved to its destination the pump may then be connected tobe driven by the engine.

Assume that when the driving of the pump is started up none of theequipment 34, 38 and 41 is yet activated to load the pump. The backpressure at the pump will then only be that due to the fluid frictionthrough the hydraulic system. It is normally desirable that under thiscondition the revolutions per minute (rpm) of the pump should be greaterthan that which the idling speed of the engine would produce.Accordingly, the plugs 55 and 65 will ordinarily be adjusted for properspring pressures and the chain 74 will be attached to a proper one ofthe positions 75a, 75b . . . 75n, so that when the pump starts up itwill develop enough fluid pressure to move piston rod 54 enough to openthe throttle enough to speed up the engine somewhat to bring the pumprpm and gallons per minute (gpm) flow to a certain desired rate which isherein referred to as a pre-set rate. Now assuming a small load is puton the pump by activation of one of the equipments 34, 38 and 41, theeffect will be to move piston 48 somewhat with no substantial movementof piston 59. This will open the throttle further to produce theincrement of horsepower neeeded to maintain constant the rpm and hencegpm. As the load increases somewhat, this same effect will continue toopen the throttle enough to create additional horesepower needed tomaintain constant the rpm and gpm. As the piston 48 and piston rod 54come close to the end of their possible travel while the fluid pressureand pressure of spring 58 are increasing, the piston 48 will have littlefurther effect on the throttle with increasing load and fluid pressure.It will have a relatively minor effect at the higher fluid pressuresbecause it takes a relatively great amount of pressure to urge thespring 58 through its last stage of compression to its maximumcompressed position. However, after the fluid pressure has becomemoderately high, which will be close to the end of travel of piston 48,the pressure has become high enough to move piston 59 substantiallyagainst the pressure of its spring 68. This will continue to open thethrottle, as the load, and hence fluid pressure, continues to increaseto higher values thereby continuing to create the horsepower required tomaintain the rpm and gpm substantially constant. Furthermore, the piston59 is effective over a wide range of the higher pressures due not onlyto the fact that as illustrated in FIG. 2, the piston 59 may have agreater travel possibility than piston 48, but also due to the fact thata given linear motion of piston rod 61 moves the position 75 through agreater distance than does the same increment of piston rod 54.

As an example, assume that the hydraulic system is capable of anoperation of from close to 0 pounds per square inch fluid pressure whenthere is no equipment load on the pump, and up to a maximum capabilityof 3000 pounds per square inch fluid pressure which may exist when themaximum equipment load is put on the system. The unit 43 may be adjustedby its plugs 55 and 65 and the hook attachments 75, 75a . . . 75n, sothat at low and moderate loads creating a fluid pressure up to, say,about 50 pounds per square inch, piston 48 is effective to control thethrottle, while there is little or no movement of piston 59. But abovethe 50 pounds per square inch pressure, piston 48 is pushed almostagainst the plug 55 and cannot move appreciably further, but piston 59will then undergo substantial increments of movement with further risingfluid pressure, and hence effectively control the throttle.

It should be understood that variations may be made from the foregoingexplanation of a generally preferred mode of operation of the throttlecontrol mechanism. Such variations can be realized by appropriateadjustments of the three adjustable devices: plug bushing 55; plug screw65; and the selection of positions 75 or 75a . . . 75n.

It will also be recognized that variations of structure may be madewithin the scope of the invention. For example types of springs orresilient means other than the coil springs 58 and 68 may be used.Although the cylinders 46 and 47 are shown in the drawing as formed in asingle block, they could if desired, be formed in separate blocks.

The diameters of the pistons and the ratio of these diameters and thespacing of the pivot points on the arm 71 are subject to selection andwill depend on the requirements of particular situations. It has beenfound that for one application piston diameters of 3/4 inch and 11/2inch respectively with a spacing of 21/8 inches between the pivotpositions has been satisfactory, and in this case the distance alongpivoted member 71 from the pivot position 73 of piston rod 54 to theposition of attachment of chain 74 to member 71 was about 21/4 inches.

The hydraulic fluid will ordinarily be oil, but it will be understoodthat some other liquid may be used.

It will be understood that the embodiments of the invention illustratedand described herein are given by way of illustration and not oflimitation, and that modifications or equivalents or alternatives withinthe scope of the invention may suggest themselves to those skilled inthe art.

I claim:
 1. In combination, an engine having a throttle arm, a hydraulicpump driven by the engine, and a throttle control mechanismsaid throttlecontrol mechanism comprising: a first cylinder with a closure at eachend thereof; a first piston reciprocatable within said first cylinder; afirst piston rod connected to said first piston and extending throughone of said first cylinder closures to the exterior of the firstcylinder; a second cylinder with a closure at each end thereof; a secondpiston reciprocatable within said second cylinder; a second piston rodconnected to said second piston and extending through one of said secondcylinder closures to the exterior of said second cylinder; a memberpivoted to both said piston rods at respective positions outside of saidcylinders; fluid inlet means into a region of said first cylinder at oneside of the first piston and into a region of said second cylinder atone side of the second piston; whereby pressurized fluid introducedthrough said fluid inlet means into said cylinders urges both saidpistons to move longitudinally within their respective cylinders; meansurging each piston to move longitudinally in the direction opposite thatin which the fluid pressure is urging it; the longitudinal axes of saidcylinders being oriented relative to each other so that when saidpistons move in the directions in which they are urged by the fluidpressure each piston has a component of motion in the direction oppositethat of the other piston; linkage means connecting said pivoted memberwith said throttle arm, and a hydraulic conduit leading from the outletof said pump to said fluid inlet means, whereby increased fluid pressureat the pump outlet moves said pivoted member in a direction whichfurther opens the throttle.
 2. A combination according to claim 1 inwhich the hydraulic pump is in a hydraulic circuit including a fluidreservoir and fluid operable equipment which when operated tends toincrease the back pressure against the pump and hence slow the speed ofthe engine, whereby the increased back pressure causes the pivotedmember to move the throttle arm in the direction which further opens thethrottle, thereby tending to overcome the tendency for the engine speedto decrease.
 3. A combination according to claim 1 in which one of thepistons has a larger diameter than the other piston.
 4. A combinationaccording to claim 3 in which the piston rod connected to the largerdiameter piston is pivoted to the pivoted member at a position of themember between the position where the member is pivoted to theconnecting rod from the smaller diameter piston and a length of themember remote from the last-mentioned position.
 5. A combinationaccording to claim 4 in which the distance between the position ofconnection of the linkage means to the pivoted member and the positionwhere the piston rod of the larger diameter piston is pivoted, isgreater than the distance between the positions of pivoting of the twopiston rods.
 6. A combination according to claim 5 in which the firstmentioned distance is about twice as great as the second mentioneddistance.
 7. A combination according to claim 4 in which the position ofconnection of the linkage means to the pivoted member is adjustablealong the length of the member.